Relation between fatty acid profile, growth rate and condition factor using a non-lethal sampling method in European sea bass.

Abstract

In several organisms including fish, lipids are the most efficient source of energy compared to other nutrients. Some fatty acids (e.g. oleic acid, palmitic acid) are known to be preferentially used by organisms to create or to store energy. Here, we aimed to understand the relationship between FA profile, individual growth performance and well-being of European sea bass (Dicentrarchus labrax). For that, we coupled the measurements of growth rate and Fulton’s condition factor (K), both widely used to estimate growth and the well-being of a fish, to an innovative non-lethal sampling method for FA analysis that allows us to measure the evolution of the fatty acid profile individually. Eighteen tagged sea bass juveniles were reared during 130 days in the same food and temperature conditions, in triplicate. White muscle subcutaneous biopsy was carried out on each fish at day 0 and day 130 for FA analysis. Fish were weighted and measured to calculate growth rate (Thermal Growth Coefficient, TGC) and K at d0 and d130. The fatty acid profiles of the three best and lowest performing fish (TGC related) were compared. The two biopsies performed over the 130 days induced no mortality. All the fish had positive TGC and showed an increase in K (1.01 ±0.15 at d0; 1.20 ±0.12 at d130). The results will be discussed trying to establish a link between FA, TGC and K, on an individual scale.